时空驱动的大规模真实感海洋场景实时渲染

Real Time Rendering of Large Scale Realistic Ocean Scenes Driven by Time and Space

针对目前计算机图形学领域对于精确的时间和空间条件驱动下大规模海洋场景的研究匮乏的现状,提出一个时空驱动的大规模真实感海洋场景实时渲染框架.首先,采用天空球代替传统天空盒进行天空背景建模,弥补天空盒灵活性和真实性上的不足;引入简化天文模型进行天体位置计算,真实展现天体运行规律;其次,引入风力驱动的统一方向谱进行海浪绘制,弥补目前图形学领域利用海浪谱建模在短波绘制效果上的不足;最后,将大气散射、海洋表面以及海下光线传播作为整体考虑,构建海面综合光照渲染模型.实验表明:该框架不仅能够真实地展现在精确的时空条件下大规模海洋场景的波浪运动以及光学效果的变化,而且能够很好地满足实时应用的需要.

Rendering large-scale ocean scenes plays an important role in simulators,movies and other aspects.Because of the complexity of the ocean and the sky,it is difficult to animate large-scale realistic ocean scenes in real time,especially under precise time and space conditions.In this paper,we present a real-time rendering framework for large-scale realistic ocean scenes.In traditional real-time ocean rendering method,the skybox method consisting of a big textured cube with six images is usually used to model the sky for its rapidity and simplicity.However,it has potential problems with seams in the edge of the skybox and it is not flexible enough.In our case,we apply a skysphere method which is convenient to position the celestial bodies and to set up the light scattering model.To show the real movement of celestial bodies,we establish a simplified astronomical model to compute the position of every single celestial body in the scene.When the wind blows over the ocean,the high frequency short wave appears first,then the low frequency long wave grows.As the wave is fully grown,the long wave will be more prominent.Researchers in graphics always focus on rendering the long wave while ignoring the short wave.We apply a unified directional spectrum for long and short wind-driven waves to draw the waves,which covers the shortage of the short wave rendering.The ocean illumination is a difficult problem for computer graphics,because both the ocean and the light source are dynamic.Via the analysis of the real ocean illumination,we take the atmospheric scattering,the ocean surface reflection and the ocean subsurface scattering as a whole,and build up a comprehensive ocean lighting rendering model.With this method,we can make the ocean waves alive,and enrich the optical effects colorfully while simulating the large-scale ocean scenes under precise time and space conditions.We demonstrate the visual realism and performance of our method in various experiments,achieving high frame rates on different desktop PCs.